May 12, 2010

Hair and eye color in adult film actresses

All right, enough talk about art and violence. Time to focus on bigger questions like "blondes or brunettes?" Adult Film Database lets you filter people by hair and eye color, although they have lots of shades of hair color. I collapsed those groups into red, blonde, dark blonde / light brown, and dark brown or black. There's going to be more error in making fine-grained distinctions based on photographs, and these are the categories used in a study of how common hair and eye colors are in the overall population. The girls are not weighted by how popular they are (e.g. by how many movies they've been in), but before I showed that among the most sought after ones darker colors prevailed.

Here are the results (click to enlarge):

For comparison, here's how frequent these colors are in Northern European populations. For eye color, green is about 2/3 as frequent as we'd expect, blue / grey is under half as common as we'd expect, while hazel / brown / black is over 5 times as frequent as we'd expect. Relative to the population, red hair is just over half as common, blonde is 1.8 times as common, dark blonde / light brown is 1/5 as common, and dark brown / black is 2 times as common.

The over-representation of the more extreme colors -- lighter blonde and darker brown -- and an under-representation of in-between colors also showed up in Maxim cover girls. It could be due to what different raters code as light blonde, dark blonde, light brown, and dark brown. It could also be that light blonde and dark brown really are over-represented because if you're a blonde-loving guy, you want them blonde, and brunette-loving guys want them dark. The more intense signals in either direction are what's chosen for.

This approach based on over-representation really misses what the data are saying, though -- namely, that men favor brunettes and dark-eyed girls, although not universally, because a higher fraction of porn girls are dark-colored than light-colored. How that distribution relates to the distribution of colors in the population is irrelevant. Over-representation only tells us indirectly about the traits a group possesses.

For example, Ashkenazi Jews are over-represented in academia, but that doesn't mean those who hire academics have a taste for Jews -- if so, shouldn't they be close to 100%? Rather, it says that Jews must be more likely than other groups to have the traits that academia truly selects for, such as high intelligence. That is where we do see close to 100% representation -- everyone in academia scores pretty well above average in IQ, especially in the departments that don't exist to house quotas or to give dumb students something to major in.

Similarly, the fact that blonde hair and blue eyes are a minority in porn girls shows that most guys don't have a thing for blondes or blue eyes. If we found that blondes were over-represented, that only means there's some other group of traits that blondes are more likely to have than others -- like maybe they have cuter faces or smoother skin (just to make something up, as I think paler people would have more damaged skin), which are things that all men truly obsess over in evaluating good looks. It's these signs of health and youth that men focus on, not so much what color her hair and eyes are. In fact, Adult Film Database has categories for bald, grey, salt-and-pepper, and white hair -- yet there are virtually no women from these groups! Like IQ for academics, having color still in your hair is a necessary condition for females to look good. What particular color it is doesn't seem to matter so much, although darker is better, so long as you don't look old or sickly.

These data cast further doubt on the idea that blondes are more likely to have whatever other traits are truly selected for, as this idea requires that the women listed as blondes be natural blondes. It's strange that blue eyes are only half as common as in the overall population, while light blonde hair is twice as common, given that light color goes together across the eyes, hair, and skin. This suggests that a lot of the blonde girls are natural brunettes -- they can disguise their hair color easily but not really their eye color. (They could use color contacts, but that doesn't keep the maintainers of a database from easily learning what their natural eye color is.)

So the picture looks like, compared to the population, lighter colors are either as common (natural light blonde hair) or less (blue eyes), suggesting that darker-colored females are more likely to have whatever other traits that really matter to males. It could be something as simple as better skin, as people with dark hair and eyes also tend to have darker skin, which doesn't age as poorly as pale skin does. Also it seems like darker hair is more voluminous and lustrous, while pale blonde hair tends more to fall flat against the scalp. And based on the wider animal world, darker pigmentation reflects a less tame nature; domesticated animals tend to get lighter eyes and coat colors. So a more wild and fun-loving nature could be another trait that brunettes are more likely to have.

It is these signals of youth and health that men truly care about -- perfect skin, vibrant hair, and an exuberant disposition -- rather than the color of hair or eyes per se. To the extent that any color preference exists, it is clearly for darker colors, especially in the eyes.

7 comments:

Am I misreading this, or are you forgetting in your analysis to control for race? Almost every single latin, black, or asian porno girl (or mixed race) is going to have brown eyes and brown or black hair. Add that to the white girls who also fit into that category and you have a large proportion.

Your analysis perhaps still stands, but I think maybe it needs a little revising. Or am I missing something?

No, what the data show is that the fraction of blue eyes is a lot lower than we'd expect if they were representative of a Northern European population. It doesn't matter whether the dark-eyed people are coming from Northern Europe or elsewhere.

You can play with the numbers to see whether the over-representation findings would still hold. Say N.E.s are 80% of the database (it includes Europeans like Czechs and Brits, not just Americans), and the other 20% are other ethnicities that are almost entirely dark-eyed. Then the weighted frequency of blue eyes would be:

0.8*0.7 + 0.2*0 = 0.56 = 56%

Still not low enough to make blue eyes equally represented. But again, this over-representation approach does not tell us what men like -- the raw data do, and they show that darker colors are preferred if any are. Over-representation only tells us whether some other, unseen beneficial traits are more likely to show up in one group than in another.

"Actually, only 1 in 6 Americans has blue eyes."

That sounds bogus. Two separate N.E. populations have frequencies around 70% (Dutch and Icelanders), and it's not going to be much lower in Britain. Again just do a weighted average to work backwards at what fraction, p, of Americans are of N.E. ethnicity, assuming that guy's estimate were true:

p*0.7 + (1-p)*0 = 0.17

Implies that only 24% of Americans are N.E. -- way off. Relax the assumption to be that blue eyes are only 50% among the N.E.s who came to America (rather than 70% among Dutch and Icelanders):

p*0.5 + (1-p)*0 = 0.17

Implies that only 34% of Americans are N.E. -- still way off. I haven't read the study he did, but clearly he chose a biased sample.

"The hair color of Caucasian Americans is said to be 68% brunette, 27% natural or dyed blonde, and 5% redhead."

That cites a psych study looking at hair color in magazines, so I doubt they performed a national representative survey, unlike the two in the link I provided.

Still, my categories are not blonde, brunette, and redhead; they distinguish the middle ground of dark blonde / light brown from the lighter blondes and darker brunettes, just like the Dutch and Icelander studies did.

So light brown and dark blonde are under-represented, but not dark browns / blacks or light blondes.

As far as I know, there's no evidence showing people with blue eyes are more socially inhibited as adults.

Associations between iris characteristics and personality in adulthoodBiological Psychology, Volume 75, Issue 2, May 2007, Pages 165-175Mats Larsson, Nancy L. Pedersen, Håkan Stattin...The idea that personality differences are related to irischaracteristics is not new. In 1965, Cattell (1965) observeddifferences in cognitive styles between blue and brown eyedsubjects and since then eye color has been found to be related to agreat variety of physiological and behavioral characteristics.Dark eyed people have on average higher scores on extraversion,neuroticism (Gentry et al., 1985), ease of emotional arousal(Markle, 1976) and sociability (Gary and Glover, 1976).However, there are a number of studies that fail to replicatethe personality findings, typically because the effect tends to fadeafter early childhood. For instance, Rubin and Both (1989) foundthat blue-eyed children in kindergarten and Grade 2 wereoverrepresented in groups of extremely withdrawn youngsters,whereas no association could be found in Grade 4 or between eyecolor and extreme sociability in any grade. Furthermore, insubjects around 20 years of age, eye color failed to account forany difference between high versus low scorers on personalitymeasures (Lester, 1987; Rim, 1983). Consequently, it has beenassumed that the biological mechanisms that may underlie theassociation between eye color and social wariness in earlychildhood tends to be ‘‘overcome’’ around age 9 when theincreasing influence of social environmental factors has gainedmomentum (Rubin and Both, 1989). To our knowledge, noresearch has been reported concerning eye color and its relationto personality since 1998, when Coplan et al. (1998) found asignificant eye color by gender interaction for socialwariness in asample of 3.5–5.5-year-old toddlers. This finding raised furtherquestions regarding the phenotypic penetrance of the suggestedbiological mechanism involved. Leading researchers in the fieldconcluded that eye color cannot be a useful marker forpersonality in older ages (Coplan et al., 1998; Rosenberg andKagan, 1989; Rubin and Both, 1989).